橡胶混凝土与常规混凝土组合桩抗震性能研究

地震中，桩基础常常因抗弯能力不足或位移过大而发生破坏.为改善桩基的抗震性能，研发了一种上部为橡胶混凝土、下部为常规混凝土的组合桩.为分析组合桩的抗震性能，在施工现场采用落锤激振模拟震源，对组合桩进行现场足尺试验研究.研究表明:桩顶荷载产生侧向约束，可增强桩基抗震性能.试验中，橡胶混凝土桩段与桩身长度比小于1/6时，荷载约束影响深度为橡胶混凝土桩段长度，橡胶混凝土桩段与桩身长度比大于1/6时，荷载约束影响深度恒为1/6桩长.桩位临近震源，橡胶混凝土桩段减震作用明显，随着桩位远离震源，橡胶混凝土桩段减震性能降低，且不再全长发挥作用.减震效率和橡胶混凝土桩段与桩身长度比值的拟合曲线呈S形，抗震设计时，不可采用持续增加橡胶混凝土桩段长度的方式提高桩的抗震性能.

Study on Seismic Performance of Rubber Concrete and Conventional Concrete Composite Pile

In earthquake， the pile foundation is often damaged due to the insufficient bending moment resistance and excessive displacement. In order to improve the seismic performance of the pile foundation， a composite pile with rubber concrete at the top and conventional concrete at the bottom was developed. In order to analyze the seismic performance of composite piles， a drop hammer was used to simulate the earthquake source， and a full-scale field test was conducted on the composite piles. The results show that load on the pile top can enhance the seismic performance of the pile foundation. In the test， when the ratio of the rubber concrete pile length to the total pile length is less than 1/6， the depth of the load constraint effect is equal to the rubber concrete pile length. When the ratio of the rubber concrete pile length to the total pile length is more than 1/6， the depth of the load constraint effect is a constant of 1/6 of pile length. The damping effect of the rubber concrete pile is significant if the pile is close to the earthquake source， while it decreases with the increase of the distance from the seismic source， and the rubber concrete section of the pile no longer plays a role in the whole length. The fitting curve of the damping efficiency and the ratio of the rubber concrete pile length to the total pile length is S-shaped. During the seismic design， it is not suitable to continuously increase the length of the rubber concrete pile to improve the seismic performance of the pile.